Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
  • C07C31/18—Polyhydroxylic acyclic alcohols
  • C07C31/26—Hexahydroxylic alcohols
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group

Definitions

• the present invention relates to a method for producing sugar alcohols by hydrogenating sugar using macroporous catalysts, the one or more metals of subgroup VIII of the periodic table alone or together with at least one metal from subgroup I or VII of the periodic table as active component (s).
• Sugar alcohols e.g. Sorbitol, mannitol, maltitol and xylitol are widely used in the food industry, cosmetics, pharmacy and on the technical sector.
• EP-A 0 773 063 describes a continuous process for the hydrogenation of Sugaring on a Raney-Ni-Al contact at 130 ° C and 150 bar pressure.
• all metals of subgroup VIII of the periodic table can be used as active metal be used. Platinum, rhodium, Palladium, cobalt, nickel or ruthenium or a mixture of two or more of it used, in particular ruthenium used as the active metal becomes.
• the metals of I. or VII. Or I. and the VII. subgroup of the periodic table which are also all in principle copper and / or rhenium are preferably used.
• macropores and “mesopores” are used in the context of the present invention as they are in Pure Appl. Chem., 45 , p. 79 (1976) are defined as pores whose diameter is above 50 nm (macropores) or whose diameter is between 2 nm and 50 nm (mesopores).
• the content of the active metal is generally from about 0.01 to about 30 % By weight, preferably about 0.01 to about 5% by weight and in particular about 0.1 to about 5 wt .-%, each based on the total weight of the used Catalyst, which preferably used in the catalysts 1 to 3 Let me say again when discussing these catalysts are.
• customary catalyst support systems for producing the catalysts according to the invention such as. Activated carbon, silicon carbide, aluminum oxide, silicon dioxide, Titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide or mixtures thereof, are used, they are each in spherical, strand or ring shape, if they are used as a fixed bed contact, as well as a split or fine-grained Granules for use in suspension. More details regarding this Support systems can be found in the discussion for the respective catalysts 1 to 3.
• sugars can be used in the present process become.
• the term "sugar” used according to the invention includes both Monosaccharides, e.g. Glucose, mannose, galactose, talose, fructose, allose, Altrose, Idose, Gulose, Xylose, Ribose, Arabinose, Lyxsose, Threose and Erythrose, Di- and trisaccharides such as Maltose, lactose, cellobiose, sucrose, melibiose and Raffinose, and polysaccharides such as e.g. Starch, starch decomposition products, cellulose and cellulose decomposition products such as e.g. Dextrin, glucose syrup, cellulose hydrolysates and starch hydrolyzates, e.g. Mais Congress Congress, asate.
• Monosaccharides e.g. Glucose, mannose, galactose, t
• Glucose is preferably added in the process according to the invention Sorbitol, mannose to mannitol, fructose to a mixture of sorbitol and mannitol, Xylose to xylitol, lactose to lactitol and maltose converted to maltitol.
• the inventive method can in the presence of a catalyst 1, the at least at least one homogeneous compound deposited in situ on a carrier a metal of subgroup VIII of the periodic table, possibly together with at least one homogeneous compound of at least one metal of I. or VII. Subgroup of the periodic table, is carried out.
• the production The catalysts are made in that a homogeneous metal compound is introduced into the reactor during the reaction with the entry and itself deposits on a support located in the reactor during the reaction.
• the homogeneous metal compound can also be converted into the reactor be introduced and during treatment with hydrogen on one Separate the carrier located in the reactor.
• in situ used in the context of the present application means that the catalyst is not manufactured and dried separately and then as it were finished catalyst is introduced into the reactor, but that the catalyst in the context of the present invention in the reactor either immediately before or is formed during the actual hydrogenation.
• homogeneous compound used in the context of the present application a metal of VIII., I. or VII. subgroup of the periodic table " or “homogeneous ruthenium compound” means that the one used according to the invention Metal compound in the medium surrounding it, i.e. of the used sugar to be hydrogenated, which is in the form of an aqueous solution, soluble is.
• the main metal compounds used here are nitrosyl nitrates and nitrates, however also halides, carbonates, carboxylates, acetylacetonates, chloro-, nitrido- and Amine complexes and oxide hydrates or mixtures thereof.
• preferred Compounds are ruthenium nitrosyl nitrate, ruthenium (III) chloride, ruthenium (III) nitrate and ruthenium oxide hydrate.
• the amount of the or the metal connection applied is not particularly limited, is from the point of view of sufficient catalytic activity and economy of the process the metal salt or the metal complex in one such amounts applied to the carrier or carriers that 0.01 to 30% by weight, based on the total weight of the catalyst, of active metal on the or Separates carriers. This amount is more preferably 0.2 to 15% by weight, in particular preferably about 0.5% by weight.
• the supports in the reactor are preferably metal nets and metal rings and steatite bodies, as described, inter alia, in EP-A-0 564 830 and EP-A-0 198 435 can be described. In the following, the within the scope of the present invention particularly preferably used carrier and their preparation are explained.
• Metallic carrier materials such as for example, are particularly preferred Stainless steels with material numbers 1.4767, 1.4401, 2.4610, 1.4765, 1.4847, 1.4301 etc. used, because they are coated by a Annealing can get a roughening of their surface.
• Kanthal is an alloy that is approximately 75% by weight Fe, about 20 wt% Cr and about 5 wt% Al.
• the carriers described above can with a layer of a palladium metal, e.g. Ni, Pd, Pt, Rh, preferably Pd, in a thickness of approximately 0.5 to approximately 10 nm, in particular approximately 5 nm, are vaporized, as also in EP-A-0 564 830 already mentioned above is described.
• a palladium metal e.g. Ni, Pd, Pt, Rh, preferably Pd
• a network is used in particular as a catalyst from annealed Kanthal, on which a Pd layer to facilitate the deposition of the active metal was evaporated to a thickness of approximately 5 nm when Carrier used.
• catalyst support systems such as activated carbon, Silicon carbide, aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, Magnesium oxide, zinc oxide or mixtures thereof, each in spherical, extruded or Ring shape, as a split, or fine-grained granules can be used.
• aluminum oxide and zirconium dioxide are particularly preferred.
• the Pore size and pore distribution are completely uncritical. It can be bimodal and all other types of carriers can also be used.
• the carriers are macroporous.
• the catalysts 2 used according to the invention contain one or more metals VIII.
• the catalysts 2 used according to the invention can be produced industrially are by applying at least one active metal of subgroup VIII Periodic table, preferably ruthenium or palladium and optionally at least a metal of subgroup I or VII of the periodic table on one suitable carrier.
• the application can be done by soaking the carrier in aqueous Metal salt solutions, e.g. Ruthenium or palladium salt solutions, by spraying appropriate metal salt solutions on the carrier or by other suitable Procedure can be achieved.
• the metal salts or metal salt solutions can be applied simultaneously or in succession become.
• the supports coated or soaked with the metal salt solution are then dried, temperatures between 100 ° C. and 150 ° C. being preferred. These supports can optionally be calcined at temperatures between 200 ° C and 600 ° C, preferably 350 ° C to 450 ° C.
• the coated supports are then activated by treatment in a gas stream which contains free hydrogen at temperatures between 30 ° C. and 600 ° C., preferably between 100 ° C. and 450 ° C. and in particular 100 ° C. to 300 ° C.
• the gas stream preferably consists of 50 to 100% by volume of H 2 and 0 to 50% by volume of N 2 .
• the application takes place one after the other, so the wearer can after each application or soaking at temperatures between 100 ° C and 150 ° C and optionally at temperatures be calcined between 200 ° C and 600 ° C.
• the metal salt solution is applied to the carrier (s) in such an amount that that the content of active metal 0.01 to 30 wt .-%, preferably 0.01 to 10 wt .-%, more preferably 0.01 to 5% by weight, and in particular 0.3 to 1% by weight on the total weight of the catalyst.
• the total metal surface area on the catalyst is preferably 0.01 to 10 m 2 / g, more preferably 0.05 to 5 m 2 / g and further preferably 0.05 to 3 m 2 / g of the catalyst.
• the metal surface was measured by the chemisorption method as described in J. LeMaitre et al., "Characterization of Heterologous Catalysts", ed. Francis Delanney, Marcel Dekker, New York (1984), pp. 310-324.
• the ratio of the surfaces is the at least one active metal and the catalyst support less than about 0.3, preferably less than about 0.1 and especially about 0.05 or less, with the lower limit being approximately 0.0005.
• Carrier materials have macropores and mesopores.
• the supports which can be used according to the invention have a pore distribution, from about 5 to about 50%, preferably from about 10 to about 45%, more preferably about 10 to about 30 and especially about 15 up to about 25% of the pore volume of macropores with a pore diameter in Range from about 50 nm to about 10,000 nm and about 50 to about 95%, preferably about 55 to about 90%, more preferably about 70 to about 90% and especially about 75 to about 95% of the pore volume of mesopores with a pore diameter of about 2 to about 50 nm are formed, the sum of the pore volumes adding up to 100% in each case.
• the total pore volume of the carriers used according to the invention is approximately 0.05 to 1.5 cm 3 / g, preferably 0.1 to 1.2 cm 3 / g and in particular approximately 0.3 to 1.0 cm 3 / g.
• the average pore diameter of the supports used according to the invention is approximately 5 to 20 nm, preferably approximately 8 to approximately 15 nm and in particular approximately 9 to approximately 12 nm.
• the surface area of the support is from about 50 to about 500 m 2 / g, more preferably from about 200 to about 350 m 2 / g, and in particular from about 250 to about 300 m 2 / g of the support.
• the surface of the support is determined by the BET method by N 2 adsorption, in particular according to DIN 66131.
• the average pore diameter and the size distribution are determined by mercury porosimetry, in particular according to DIN 66133.
• the catalyst 3 used according to the invention can be produced by that the carrier material in the form of a metal mesh or a metal foil one after the other heated in air, cooled and in vacuum with the one described above Active metal or the combination of two or more thereof is coated, then the coated carrier material is cut, deformed and finally closed a monolithic catalyst element is processed.
• This catalyst and its manufacture is already described in detail in EP-A-0 564 830 and US 4,686,202 described, the relevant content in full in the context of present application is included. The following are intended only once more the essential principles of the preparation of this catalyst or the preferred ones Embodiments of the same are briefly discussed, with respect to the used active metals that applies to the catalysts 1 to 2 said.
• Stainless steels such as those with the material numbers 1.4767, 1.4401, 2.4610, 1.4765, 1.4847, 1.4301 etc., are particularly suitable as metallic carrier materials in the form of metal foils or metal meshes, as they are roughened by tempering their surface before being coated with active components can.
• the metallic supports are heated in air at temperatures of 600 to 1100 ° C., preferably 800 to 1000 ° C. for 1 to 20, preferably 1 to 10 hours, and cooled again. This pretreatment is crucial for the activity of the catalyst. After this carrier treatment at elevated temperature, the active component is coated.
• the carrier is coated with the active component at the same time or in succession in a discontinuous or continuous manner by means of an evaporation device, for example electron beam evaporation or sputtering device, in vacuo at a pressure of 10 -3 to 10 -5 mbar. Tempering under inert gas or air can be followed to form the catalyst.
• an evaporation device for example electron beam evaporation or sputtering device, in vacuo at a pressure of 10 -3 to 10 -5 mbar. Tempering under inert gas or air can be followed to form the catalyst.
• catalyst layers described here is about to produce disordered and disturbed polycrystalline layers or clusters. Therefore, vacuum conditions are usually not particularly good required. You can also by alternately evaporating active components and structural promoters the active components are very fine crystalline or Generate in a cluster.
• the catalyst can be built up systematically here, for example in an evaporation plant with several different evaporation sources. So you can for example, first an oxide layer or one by reactive evaporation Apply adhesive layer on the carrier. Active components can be placed on this base layer and manufacture promoters in multiple alternating layers. By Intake of a reactive gas in the recipient can be made from promoter layers Oxides or other compounds are generated. Annealing processes can also be interposed.
• the active components have such good adhesive strength that you can now cut them, deform and process to monolithic catalyst elements.
• a very simple monolithic catalyst can be obtained by looking at the catalyst mesh or the catalyst foil is deformed by means of a gear roller and smooth and corrugated fabric or foil rolls into a cylindrical one Monoliths with similar vertical channels. But you can also choose any Form static mixers from this catalyst material because of the adhesive strength the catalyst layer is sufficiently high.
• the monolithic catalyst elements produced in this way in the form of mixing elements are installed in a reactor and with a reaction liquid to be reacted applied.
• the hydrogenation is generally at a temperature from about 50 to about 140 ° C, preferably about 80 to about 120 ° C.
• the pressures used are in the Usually above about 50 bar, preferably about 80 to about 300 bar, particularly preferably about 100 to about 160 bar.
• the methods of the invention can be either continuous or discontinuous be carried out, with the continuous process being preferred is.
• the respective catalysts can can be used as fixed bed catalysts or in suspension.
• the catalysts of the invention are used as fixed bed contacts.
• suspension mode the inventive methods are preferably in one Reactor carried out, which comprises a device having openings or channels a hydraulic diameter of 0.5 to 20 mm, preferably 1 to 10 mm and in particular has 1 to 3 mm, a so-called bubble column. Further details regarding this special reactor can be found in DE-A 196 11 976, the content of which is fully in the context of the present application is recorded.
• the amount of hydrogenation is intended sugar about 0.05 to about 3 kg / l catalyst per hour, more preferably about 0.1 to about 1 kg / l catalyst per hour.
• any gases can be used as hydrogenation gases, the free hydrogen contain and no harmful amounts of catalyst poisons, such as CO.
• catalyst poisons such as CO
• reformer exhaust gases can be used.
• pure hydrogen is used as the hydrogenation gas.
• the sugars to be converted are used in pure form as aqueous solutions.
• concentrations of the sugar are preferably from about 15 to about 70% by weight, more preferably about 30 to about 55% by weight, based on the Total weight of the aqueous solution.
• the pH of the aqueous solution is generally about 3.5 to about 10, preferably about 3.5 to about 8.
• the aqueous sugar solutions are due to minor contamination from sugar acids in general neutral or slightly acidic. You can in a manner known to those skilled in the art the desired pH value can be set.
• the hydrogenation of the Sugar can also be carried out without changing the pH, one later - possibly complex - separation of the substances used for pH adjustment are used.
• the conversion of the sugar in the hydrogenation is almost completely.
• a maximum of 0.1% by weight of the sugar used in the Product solution can be demonstrated.
• the sugar alcohols are almost epimer-free Shape, i.e. the content of epimers in the product is in general not more than 1% by weight, preferably not more than 0.5% by weight, and with higher Purity (> 99%).
• the heavy metal content is generally below 10. preferably below 5 and in particular below 1 ppm.
• the present invention particularly relates to the use of the Processes described herein for the manufacture of sugar alcohols which are nearly Are epimer-free.
• the sugar alcohol (s) obtained after completion of the hydrogenation Product solutions containing can, if desired, according to conventional Methods such as Spray drying, freeze drying, drying rollers or Vaporizing, concentrating.
• they can be concentrated or unfocused without a further cleaning step to be processed further.
• sugar alcohols thus obtained in particular sorbitol, can be used as a food additive, especially as sweeteners, moisture stabilizers in food as well as in cosmetics and pharmaceutical products, as raw materials for the production of polyurethane, especially for the production of hard polyurethane foams be used.
• the sorbitol produced according to the invention can be used in particular for the synthesis of vitamin C can be used.
• the present invention further relates to a method for the synthesis of vitamin C starting from sorbitol, which is characterized in that the starting material Obtain sorbitol according to one of the methods described herein becomes.
• Catalysts in the hydrogenation of sugar to sugar alcohols brings advantages in that in the sugar alcohols obtained in the hydrogenation no significant traces of metals in colloidal or ionic form, such as by decomposition or "bleeding" of the catalysts, in particular can arise from the chelating effect of the polyhydroxy compounds, must be demonstrated.
• the metal content of the raw products is generally not more than 1 ppm. This eliminates the need for numerous prior art processes necessary separation of the heavy metals from the respective obtained as a crude product Sugar alcohols. The procedures are thus much simpler, cheaper and more ecological.
• the sugar alcohols obtained as raw products generally meet the commercial purity conditions, such as according to the German Pharmacopoeia (DAB), Food Chemical Codex (FCC) or Joint Experts Committee on Food Additives (JECFA), and therefore need before further processing e.g. not to be further cleaned in the food sector.
• DAB German Pharmacopoeia
• FCC Food Chemical Codex
• JECFA Joint Experts Committee on Food Additives
• a meso / macroporous alumina carrier in the form of 4 mm extrudates which had a BET surface area of 238 m 2 / g and a pore volume of 0.45 ml / g, was mixed with an aqueous ruthenium (III) nitrate solution , which had a concentration of 0.8 wt .-%, soaked.
• 0.15 ml / g (approximately 33% of the total pore volume) of the pores of the carrier had a diameter in the range from 50 nm to 10,000 nm and 0.30 ml / g (approximately 67% of the total pore volume) of the pores of the carrier had a pore diameter in Range from 2 to 50 nm.
• the volume of solution absorbed by the carrier during the impregnation corresponded approximately to the pore volume of the carrier used.
• the support impregnated with the ruthenium (III) nitrate solution was then added Dried 120 ° C and activated (reduced) at 200 ° C in a water stream.
• the so made The catalyst contained 0.5% by weight of ruthenium, based on the weight of the Catalyst.

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• 1998
  • 1998-04-07 DE DE19815639A patent/DE19815639A1/de not_active Withdrawn
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